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Thread: Yamaha Enticer 250 Carb Change

  1. #131
    Senior Member Improved
    Join Date
    Oct 2006
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    Northern IL
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    301


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    Hi Gary,
    My Q-2 was what was originally in my new carb that I purchased. The specs on the carb stated that it was a 159 Q-2. It is very difficult for me to read even with magnifying glass. I was able to make out the 159 & the Q2 part on it so I have no reason to doubt the specs I was given. It is in the sled now. It can make some sense that a somewhat rich lower end can help the sled take off better. When racing other sleds in the past it was always a good plan to have a fairly rich pilot and a leaner main for best drag results. I have not messed with the other jets very much. The needle jet (Tube) is just above the pilot in the fuel circuits. I have attached a jet chart I found that shows where these are in progression. Mine definitely likes the Q-2 better with either needle I have.

    After saying all this I would like to suggest changing the primary spring if this sled is not to be ridden by a child or timid rider. Mine now takes off really well with skis in the air if you want to. I am using the Blue-White spring from the attached chart and a couple shims in the primary. I did the math and the lower rate with the higher preload & the additional shims is almost exactly the full compressed tension with the stock spring. This really makes it take off great and also holds the RPMs a little higher when you are going slow. This spring has been out of production for many years but I had my local dealer do a search and he found one just last year at another dealer. Hopefully there are still some left. I also took my secondary apart this last weekend with the plan to add a little more twist to the spring. I figure that it has been in there for 41 year under tension so I am sure it has lost some of it's original value. I saw somewhere online that they had extra holes for adjustments just like the other Yamaha secondaries. I had never taken an Enticer secondary off or apart even though I had owned a few. Wow what an unbelievable pain in the A$$. Once I got it apart guess what. No extra holes. I drilled my own about 50* tighter than the way it was. I drilled an identical hole 180* across from the one I drilled for the spring just in case this small hole would effect clutch balance in some way. Probably not enough but I am a nut about that kind of thing. That seemed to be about right by some miracle. It backshifts better and brought my higher speed rpms up a little like I was hoping for. I have no tach so this is all by ear and feel. If this sled is for a beginner maybe you could try to find an original set of primary & secondary springs. I am thinking this is part of the problem. One more thing. These little 250s come geared to do between 60 & 65 MPH. That is higher that needed unless you are under 100 pounds and on a icy road. I dropped my top sprocket tooth down one and I still have a theoretical top speed of between 55 & 60 MPH. It all helps the little sled have a better chance. On a simpler note you do need to verify that your clutches move freely, rollers are good, & your belt is in spec like you mentioned before I wrote this novel.

    Good Luck !
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